An OTP memory circuit is a non-volatile memory circuit with a simple process and low cost which is widely used in integrated circuit designs. Existing OTP memory circuit may comprise single-ended floating gate OTP memory circuit, fuse OTP memory circuit, and anti-fuse OTP memory circuit etc. A single-ended OTP memory circuit may often comprise a current-sense amplifier which is configured to compare a memory current signal to a reference current signal. Stored information of the OTP memory circuit will be read out according to the comparison result of the current-sense amplifier. In such instance, an additional reference circuit is needed to generate the reference current signal, wherein the reference circuit may mismatch with the memory circuit resulting in instability of the OTP memory circuit.
In a fuse OTP memory circuit, the fuse is blown typically with using an over-current flowing through it, so that a resistance value of the fuse is changed from tens of Ohms to tens of thousands of Ohms or higher for programming. Oppositely, in an anti-fuse OTP memory circuit, a resistance value of the anti-fuse is changed from tens of thousands of Ohms to tens of Ohms for programming. However, a fuse/anti-fuse operated as an OTP storage material is based on its dielectric breakdown characteristics. Resistance of a fuse/anti-fuse during programming is changed, and different fuse/anti-fuse has different resistance, so using a fuse/anti-fuse as a memory has stability problem. Meanwhile, a fuse OTP memory circuit needs a high-pressure storage transistor, thus the cell area of the OTP memory circuit is relatively large. In addition, a high programming voltage may be required in such application which is also a challenge for design and optimization of peripheral circuits.
Accordingly, a Floating gate Avalanche-injection Metal-Oxide Semiconductor (FAMOS) OTP memory circuit with stability, smaller area and less power dissipation is desired.